CN106492874A - A kind of formula and application conditions for preparing 5 Hydroxymethylfurfural effective catalysts - Google Patents

Abstract

The invention discloses a method for preparing 5-hydroxymethylfurfural by using a high-efficiency solid acid catalyst to catalyze glucose dehydration. The formula composition of the high-efficiency solid acid catalyst is: Mg _a Zr _b Cr _c X _d . In the prescription composition of described high-efficiency solid acid catalyst, Mg is magnesium, Zr is zirconium, and Cr is chromium, and X represents a kind of in Fe (iron), Co (cobalt), Ni (nickel), and the high-efficiency solid acid catalyst In the formula composition, a, b, c, and d are molar stoichiometric ratios, and the value ranges of the molar stoichiometric ratios are: a=0.3-0.5, b=0.2-0.4, c=0.2-0.3, d=0.1-0.4; The carrier of the high-efficiency solid acid catalyst adopts hydrogen type 5A molecular sieve HZSM‑5. The invention also provides the preparation method of the solid acid catalyst and the catalytic reaction process method. The reaction condition of the catalyst to catalyze the dehydration of glucose is relatively mild, and the energy consumption is low. Compared with inorganic acids such as sulfuric acid as a catalyst, the catalyst does not generate waste acid liquid during use, and the conversion rate of glucose and the selectivity of generating 5-hydroxymethylfurfural can both reach more than 99%.

Description

A kind of formula and application condition for preparing 5-hydroxymethylfurfural high-efficiency catalyst

technical field

The invention relates to a catalyst preparation method and application conditions, that is, the formulation and application conditions of a high-efficiency catalyst for preparing 5-hydroxymethylfurfural by using glucose.

Background technique

Cellulose is an abundant biomass resource on the earth. As a natural polymer, its structural monosaccharide is glucose, and the monosaccharide of starch is also glucose. Glucose obtained by hydrolysis of cellulose or starch is further dehydrated to obtain an important platform compound 5-hydroxymethylfurfural, which can be used to synthesize many biofuels and biomaterials. However, in the absence of a catalyst, the conversion rate and selectivity of 5-hydroxymethylfurfural produced by high-temperature dehydration of glucose in an aqueous solution are very low. Utilizing inorganic acids such as sulfuric acid as a catalyst for dehydration can obtain a higher conversion rate, but the formation of The selectivity of 5-hydroxymethylfurfural is very low, and the 5-hydroxymethylfurfural obtained by dehydration is easy to be further decomposed into other by-products.

Contents of the invention

In order to overcome the defect of poor selectivity of 5-hydroxymethylfurfural prepared from inorganic acids such as sulfuric acid as the dehydration of glucose, the present invention provides a formulation and preparation method of a solid acid catalyst. The catalyst not only has high catalytic activity, but also can achieve very high conversion rate, and the selectivity to generate 5-hydroxymethylfurfural is very high.

The technical scheme that the present invention solves technical problem adopts is:

A multi-component composite solid acid catalyst is adopted, and the formula composition of the effective catalytic component of the composite catalyst is: Mg _a Zr _b Cr _c X _d . Wherein Mg is magnesium, Zr is zirconium, Cr is chromium, and X represents one of Fe (iron), Co (cobalt) and Ni (nickel). a, b, c, and d are molar stoichiometric ratios. a=0.3-0.5, b=0.2-0.4, c=0.2-0.3, d=0.1-0.4; the carrier of the composite catalyst adopts hydrogen type 5A molecular sieve HZSM-5.

The steps of the preparation method of the composite catalyst are as follows: take an appropriate amount (the amount of the reagent is controlled by the molar ratio of various metals within the range of the above formula composition) Mg(NO ₃ ) ₂ 9H ₂ O, Zr(NO ₃ ) ₄ 5H ₂ O, Cr (NO ₃ ) ₃ 5H ₂ O, Fe(NO ₃ ) ₃ 9H ₂ O (or Co(NO ₃ ) ₂ 6H ₂ O or Ni(NO ₃ ) ₂ 6H ₂ O) in 0.5L distilled water , after being heated to 70-80°C to fully dissolve, add 5A molecular sieve HZSM-5 whose mass is 6-8 times the total mass of the metal in the above reagent, and raise the temperature to 90-95°C to stir thoroughly, and evaporate the water to obtain the slurry The material is dried at 105-110°C for 9-10h, then the dried material is moved into the muffle furnace, and roasted in the air atmosphere for 5-7h, the roasting temperature is 600-650°C, the roasted material is moved out of the muffle furnace, cooled to room temperature, and ground Into powder form for later use.

Composite catalyst catalyzes xylose to prepare 5-hydroxymethylfurfural using conditions and methods as follows: prepare a certain amount of 20-43% (mass percentage) concentration of glucose aqueous solution and place it in an autoclave, and the charge accounts for 2/2 of the autoclave volume Between 3-3/4, the powdery composite catalyst prepared by the above method is added at the same time, and the catalyst consumption accounts for 10-16% of the glucose mass. The reaction pressure is controlled at 1.5-2.5atm, the reactor is heated from room temperature to the preset temperature, the heating rate is 20-25°C/min, the preset temperature is 270-285°C, and the preset temperature is maintained for 2-2.5h. During the reaction Keep stirring well. After the reaction, cool the material to room temperature, filter and separate, the catalyst can be recycled 5-8 times without any treatment, and the catalytic activity does not decrease significantly. Generally, after 10 times of use, it needs to be calcined at 600-650°C for 1-2 hours to remove a small amount of coking on the surface, and the catalyst activity is basically completely restored.

The beneficial effects of the present invention are reflected in the following aspects: a high-efficiency solid acid catalyst is provided for the preparation of 5-hydroxymethylfurfural by dehydration of glucose, the catalyst is cheap, the preparation method is simple, non-toxic and safe, and can be recycled; The catalyst catalyzes the dehydration of glucose to prepare 5-hydroxymethylfurfural. The reaction conditions are relatively mild and the energy consumption is low. Compared with inorganic acids such as sulfuric acid as a catalyst, waste acid liquid will not be generated during the use of the catalyst, and the solid acid composite catalyst of the invention has a greatly improved selectivity for 5-hydroxymethylfurfural formation.

specific embodiment

The present invention will be further described below in conjunction with embodiment:

Example 1

Take 0.5mol Mg(NO ₃ ) ₂ ·9H ₂ O, 0.2mol Zr(NO ₃ ) ₄ ·5H ₂ O, 0.1mol Cr(NO ₃ ) ₃ ·5H ₂ O, 0.3mol Fe(NO ₃ ) ₃ ·9H ₂ O was placed in 0.5L of distilled water, heated to 70°C and fully dissolved, then added 450 grams of 5A molecular sieve HZSM-5, and the temperature was raised to 95°C to fully stir, evaporated to dryness, and the obtained slurry was dried at 110°C for 9 hours. Then the dried material was moved into the muffle furnace, and roasted in the air atmosphere for 6 hours, the roasting temperature was 610°C, the roasted material was moved out of the muffle furnace, cooled to room temperature, and ground into powder for later use.

Composite catalyst catalyzes glucose dehydration to prepare 5-Hydroxymethylfurfural using conditions and methods as follows: prepare 200 grams of 35% (mass percentage concentration) glucose aqueous solution and place it in an autoclave, and the charge accounts for 2/3 of the autoclave volume, At the same time, the powdery composite catalyst prepared by the above method was added, and the catalyst consumption was 7 grams. The reaction pressure is controlled at 2atm, the reactor is heated from room temperature to the preset temperature, the heating rate is 25°C/min, the preset temperature is 275°C, and the preset temperature is maintained for 2h, and the reaction process is kept fully stirred. After the reaction, the material was cooled to room temperature and separated by filtration. Analysis of the filtrate showed that the conversion rate of glucose was 99.2%, and the selectivity of glucose dehydration to prepare 5-hydroxymethylfurfural was 95.9%.

Example 2

Take X in Mg _a Zr _b Cr _c X _d as Co, that is, when preparing the catalyst, replace Fe(NO ₃ ) ₃ 9H in Example 1 with the active ingredient precursor gas Co(NO ₃ ) ₂ 6H ₂ O ₂ O, the dosage remained unchanged, 0.3 mol was still used, and other conditions were exactly the same as in Example 1. Analysis of the filtrate after the reaction showed that the conversion rate of glucose was 99.8%, and the selectivity of 5-hydroxymethylfurfural prepared by dehydration of glucose was 98.6%.

Example 3

The X in Al _a Zr _{b Bic X d is} taken as _Ni , that is, when preparing the catalyst, the active component precursor gas Ni(NO ₃ ) ₂ ·6H ₂ O

Instead of Fe(NO ₃ ) ₃ .9H ₂ O in Example 1, the amount remains unchanged, still 0.3 mol, and other conditions are exactly the same as in Example 1. After the reaction, analysis of the filtrate shows that the conversion rate of glucose is 99.9%, and the dehydration of glucose The selectivity of preparing 5-hydroxymethylfurfural is 99.8%.

It should be understood that the examples and implementations described herein are for illustration only, and those skilled in the art can make various modifications or changes based on them, all of which belong to the protection scope of the present invention without departing from the spirit of the present invention.

Claims (3)

1. A catalyst formula and application conditions for preparing 5-hydroxymethylfurfural by catalyzing glucose dehydration with an efficient solid acid catalyst. The formulation composition of the solid acid catalyst in the present invention is: Mg _a Zr _b Cr _c X _d . Wherein Mg is magnesium, Zr is zirconium, Cr is chromium, and X represents one of Fe (iron), Co (cobalt) and Ni (nickel). a, b, c, and d are molar stoichiometric ratios. a=0.3-0.5, b=0.2-0.4, c=0.2-0.3, d=0.1-0.4; the carrier of the composite catalyst adopts hydrogen type 5A molecular sieve HZSM-5. 2. the preparation method step of composite catalyst in above-mentioned claim 1 is: take appropriate amount (reagent consumption controls various metal molar ratios in the scope that above-mentioned prescription forms) Mg(NO _{3 ) 9H 2 O} , Zr(NO ₃ ) ₄ 5H ₂ O, Cr(NO ₃ ) ₃ 5H ₂ O, Fe(NO ₃ ) ₃ 9H ₂ O (or Co(NO ₃ ) ₂ 6H ₂ O or Ni(NO ₃ ) ₂ 6H ₂ O ) in 0.5L of distilled water, heated to 70-80°C to fully dissolve, then add 5A molecular sieve HZSM-5 whose mass is 6-8 times the total mass of the metal in the above reagent, and raise the temperature to 90-95°C to fully stir , evaporate the moisture, and dry the obtained slurry at 105-110°C for 9-10h, then move the dried material into the muffle furnace, and roast it under the air atmosphere for 5-7h, the roasting temperature is 600-650°C, and the roasted material is removed from the muffle furnace furnace, cooled to room temperature, and ground into powder for later use. 3. adopt the formula described in above-mentioned claim 1 and 2 and the efficient composite catalyst Mg _a Zr _b Cr _c X _d catalytic glucose dehydration that obtains with preparation method and the reaction process and the condition of 5-hydroxymethyl furfural: the reaction raw material of preparation The glucose aqueous solution concentration is 20-43% (mass percentage), the reactor adopts an autoclave, the charging amount accounts for between 2/3-3/4 of the volume of the autoclave, and the catalyst consumption accounts for 10-16% of the xylose mass. The reaction pressure control range is 1.5-2.5atm, the heating rate of the reactor from room temperature to the preset temperature is 20-25°C/min, the preset maximum reaction temperature of the reactor is 270-285°C, and the maintenance time at the preset temperature is 2 -2.5h, keep fully stirring during the reaction. After the reaction, cool the material to room temperature, filter and separate, and the activation condition after the catalyst is coked: roast at 600-650°C for 1-2h.